The invention relates to a clamping device for clamping a work piece at a rotating spindle of a machine tool and in particular at a balancer.
A clamping device of this type is known from the German utility model DE 299 80 181. The known clamping device is comprised of a base body or a base body unit with a receiver opening concentric to the spindle, into which receiver opening a coupling shaft of the work piece can be axially inserted from a face end. Said coupling shaft is typically a respective section of a tool holder or of a tool chuck.
In general, but in particular also, where the clamping device is a component of a balancer, high demands exist with respect to the coaxial arrangement of the work piece or the tool holder or the tool chuck and the base body. The desired coaxiality is assured in the prior art, in that the coupling shaft is configured as a centering cone, which is pulled into an accordingly configured conical receiver at the base body or the base body unit. In said prior art, the centering cone and the accordingly configured conical receiver are designated as fit surfaces.
As already indicated by the term “fit surface”, in order to be able to center in this manner with the desired precision, the centering cone of the coupling shaft and the conical receiver associated therewith each have to be fitted very closely, so that the centering cone and the conical receiver associated therewith mate “flush”. Greater tolerances and in particular angle deviations lead to malfunctions and therefore are not permissible.
This means, however, that only work pieces or tool holders, which comprise a particular tightly fitted coupling shaft, can be clamped with the same base body unit. When work pieces or tool holders shall be clamped with a slightly different coupling shaft, it becomes necessary to replace the base body unit with another base body unit, which in turn comprises an accordingly configured conical receiver. For this purpose, the particular base body unit must be unthreaded from the hollow spindle, and the other base body unit must be threaded onto the hollow spindle. It is self-evident that this generates considerable complexity.
In view of this, it is an object of the invention to show an option how work pieces or tool holders with various coupling shafts or even centering bore holes can be clamped without replacing the base body unit.